I think I might have discovered the biggest cause, by the process of elimination.
I usually leave 4 or 5 sites up in tabs all the time. For the past few days, I have eliminated Drudge from that list and so far, after several days, no lock ups.
I am leaning toward concluding that there is something about the updates on Drudge, coupled with the usual Firefox/Waterfox refusal to let go of RAM, that were causing the lockups.
That is interesting. I have to say I never visit Drudge’s site...